Nikaido Kaho is a daughter of a rich family and her whole life everyone's been nice to her. When moving to her new high school dormitory, she almost gets hit by a truck but is saved by a boy. It's love at first sight for Kaho but when asking him his name, he tells her she's weird. Kaho is shocked since it's the first time anyone's ever said mean things to her. Soon enough, she finds out that the boy who saved her lives in the same dormitory and so she bravely confesses her love. The boy says his name is Kanade and agrees to go out with her. Unfortunately, the following day Kaho finds out that her first boyfriend is a 5th grader. 神·小学生。 二阶堂夏步（堀江由衣 配音）是个名副其实的千金大小姐，自幼备受呵护，不懂如何与同龄人来往，渐渐地养成毫无自信心、消极待物的性格。以升学为契机，她终于摆脱父母束缚，一个人搬进了住满各式租客的华住庄。在搬家当天，夏步险遭车祸，千钧一发之际，一个大帅哥（樱井孝宏 配音）及时出现，不但救了她一命，还狠狠训斥了她一顿。夏步对其一见钟情，正苦恼之际，她发现这个大帅哥居然和自己住在同一屋檐下。夏步冲动之下对其表白，然而这个有着帅气外表和173cm身高的大帅哥，竟然是个小学生！高中千金大小姐和逆天小学生“五年一班高桥”的名为“怪兽”的恋爱物语，正式展开。 本剧改编自日本漫画家日吉丸晃的同名漫画作品。
